Floral structure, anther development and pollen dispersal of Halophytum ameghinoi (Halophytaceae).

POZNER, R.; COCUCCI A. A.

INTERNATIONAL JOURNAL OF PLANT SCIENCES

Año: 2006 vol. 161 p. 1091 - 1098

1058-5893

A developmental and anatomical study of the staminate flowers of Halophytum ameghinoi showed decussate tepal aestivation, a residual growth of the receptacle after stamen inception, Monocotyledoneous and Basic type of anther wall development, secretory, binucleate tapetal cells, tetrahedral tetrads, and binucleate pollen grains. A vacuolate stage in the archesporial cells, the structure of endothecial thickenings, and a mechanism of anther dehiscence by connective contraction are new autapomorphies for this family. Anemophily is confirmed (Plantago-type syndrome), and field studies of pollen release showed a subtle mechanism involving rigid anther wall structure, versatile anther insertion and abaxial subterminal pores. In air currents, while anthers flutter with pores directed upwind, pollen is extracted presumably by a cavitation effect of the hooded anther tip. In a phylogenetic context, anemophily of Halophytum is of isolated occurrence within Caryophyllales, and uniovulate ovaries in sister clades probably represent a prerequisite for evolution of anemophily